Propeller shaping machine



July 5, 1938. J. R. ALBERS ET AL 2,122,631

' PROPELLER SHAPING MACHINE Filed oct. 2s, 1955 2 sheets-sheet 1 -July 5, 1938. J. R. ALBERS Er AL PROPELLER SHAPING MACHINE Filed Oct. 28, 1955 2 Sheets-Sheet 2 Patented July 5, 1938 UNITED STATES PATENT OFFICE PROPELLER SHAPING MACHINE poration cf Minnesota Application October 28, 1935, vSerial No. 47,190

Claims.

Our invention relates to a machine for shaping wooden propellers.

An object of our invention is to provide a shaping machine which efficiently shapes the pro- 5 peller blades without the necessity of hand shaping.

A further object of our invention is to provide such a machine which will shape both the pitch and the airfoil curve of the blade merely by feeding a blank strip of wood through the machine.

A further object of our invention is to provide a machine of this type which will provide an accurate pitch and airfoil curve to the blade at all points along the surface thereof.

l5 A fur-ther object of our. invention is to provide such shaping means which will accurately shape the blade -in spite of the gradual taper from the ends thereof to the hub portion.

A further object of our invention is to provide the above mentioned means in a machine of simple construction which can .be manufactured at a reasonable cost.

With these and other objects in view, our invention consists in the construction, arrangement and combination of the various parts of our device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in our claims, and illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of the machine,

Figure 2 is a plan view of the same showing the pitch cutter and the airfoil cutter,

Figure 3 is an enlarged sectional detail taken along the lines 3--3 of Figure 2,

Figure 4 is an enlarged detail in section taken along the lines 4--4 of Figure 2 and showing the cutting operation in advanced position,

Figure 5 is a section taken generally along the lines 5-5 of Figure 4,

Figure 6 is a similar section, except showing the airfoil cutting blades,

Figure 7 is an enlarged detail' of the propellerl dropping mechanism,

Figure 8 is a further view of the same, and

Figure 9 is a plan view of the finished propeller.

The principal diiiiculties encountered in propeller shaping is that of attaining an accurate curve and pitch. The' wooden propellers now made by hand are susceptible to human error, and it is our intention to show in our invention that we have provided a machine which will accurately cut the sectional contour of the blades with a minimum of time and effort. The diniculties encountered in any machine for cutting Wooden blades would principally reside in providing a correct airfoil curve regardless of the tapering thickness of the blade. We shall also show how we have accomplished this result.

We have used the character Il) to indicate gen- 5 erally the frameworks supporting the machine. The frameworks support the channel members II, and it will be noted that there are two machines, one for cutting the pitch, and the other the airfoil. Both machines are practically iden- 10 tical, with the exception of the differences which will be explained later, and therefore the description will apply to both types, with, of course, the exceptions noted. In Figure 2, it will be assumed that the lower machine is the one for cut- 15 ting the pitch. Amxed Within the channel H are the two lengthened angle irons I2. In using the machine, first .a fiat rectangular strip of wood is cut out suitably with a band saw or by other means to the shape as shown in Figure 9 which 20 is the flat surface shape of the finished propeller. Approximately one-half of the length of the propeller, or from one tip to the center, is bolted upon the platform member l5. The platform member I3 is preferably made of wood, and in- 25 cludes the bevelled top I4, which bevel is the same .as the pitch of the propeller. The flat strip is indicated by the character I5 as shown in Figure 3. Attached to the platform I3 is the substantially cylindrical member I6 which re- 30 ceives the further shaft Il. The extremity of the shaft I'I is attached at one side to the square portion I8 and to the other end to the circular portion IS. I'he circular portion I9 extends into the further square 2G which is integrally formed 35 therewith. The portion I9 (see Figure 7) extends into the ear 2I and also into the trip lever 22 which is slightly offset as shown in Figure 3, The trip lever 22 includes the bevelled ends 23 which terminate at a point as shown. To the 40 ear 2| is affixed one end of the tension spring 24, the other end of which is aixed to the platform I3 at 25. l

It will be noted that the square portion 2U and also I8 are set off-center, which provides an 451:

important feature in the machine. A further strip 26, which is attached at 2l to the platform I3, acts as a stop member tov limit the downward movement of the trip lever 22. The forward end of the platform I3 includes the further squared 59'.'

The propeller shape, which has already been cut out, is now placed upon the platform or carriage I3, and the end is forced into the small points 38 in the keep-plate 29 (see Figure 4). The U shaped clamp 3I is then brought over the strip I5 and is tightly clamped thereto by means of the cam lever 36 which is adapted to bear against the projections 11` of which` there are two, which projections are rigidly attached to the carriage I3. The carriage I3, which is now carrying the attached strip or blank4 forma is then fed into the machine by sliding the squared portions I8, 20, and the end square portions 28 along the angle irons I2'. As the strip` I5 is feci into the machine, it reaches the cut-v ting members which will now bedescribed.

The cutting members on the pitch forming machine comprise the flat platesY 3.1 which arerigidly attached to the square metal block 38 on opposite sides thereof. The plates areattached by-` means .of the cap screws 38Ywhich are received within the slots 1li,V which slots are lengthened fory adjusting the cutting depth of ther blades. 'Ihe plates 31 are bevelled at 4|-, The square blocks 33A extend into the integral shafts 4I)y which pass through suitable bearings 4I and 42= and the pulleysl 43 are attached thereto. A. semi-cylindricalhousing Mis-attached abouty the cutting members and is spaced therefromby means of suitabl-e spacers 45, and is secured by meansof the further bolts 46, which bolts pass into the enlarged anglev member 41 which extends a fairly substantialdistance above'the channel member II.

The blades are so adjusted that they will cut a suitablel depth in the member I5 to provide t -e proper thickness of the blade, and of course are adjusted so thatthey both cut in the same circle, which circle is indicate-d by the character 48'.y

The member I3 is tapered slightly, and the square members .9.8l at the forward end of the carriage I3 support the platform I3 slightlyaboveV the level` of the rear end so that the total resii is` thatv the carriage I3 tapers gradually downl .,Wardly towards the rear thereof.

Both machines are run by-means of the shaft 49 which is-attached to the large pulley 50 and the other pulley 5I. The shaft 49 is driven by means of .thebelt 52y which is suitably driven by means off an-electric motor. er other means. The belt 52.passes over the pulley 53, and surrounding yboth enlarged pulleys 50 and 5I are the further belts 5 4 which` pass over the pulleys 43. It will be noted that the pulleys'43 are considerably smaller than-therpulleys5l so that avery high speed of rotation is imparted to the blade members 31.. The circle of rotationof the blades is clockwiser as shown in the drawings andv againstthe direction .of motion of the carriageA I3. Achip breaker. is-providedwhich comprises the plate 55;.r (see. Figure 4') upon which rests a fairlyfheavy weight 5B to `which, isattached at 51 thevtensionspring. 58, the other end of which is attached at 59,fto,the casing 44. The edge` ofithe plate 5.5' is placed so that: it: justclears the. rotating. bevelled points 4Iof` the plates 31, and the iunctionrof this plate is" to y prevent the breaking: off of large pieces` which lwould tend tc chip'oif from .the wood, since itlisplacedclosefto the surface, thereof and prevents@ such injuriousleiects. The plate 55: is at.-v tachedv to the post 6J' whichaterminatesin the bearing. B2; which receives, the end B3f of the U` shaped member B4^=which are inuturnattached to thegcasing; 44 at` S5. The. -casings arescutiawayat so that the weight will be received therein...

The spring 58 supports 'the plate 55 above the surface of the work.

Figure 4 illustrates the use of the carriage with the strip I5 attached thereto wherein the strip is being pushed through the machine by the operator. As it travels, the blades are cutting at a high rate of speed, and they cut the strip I5 along the surface 61 which is indicatedalso by the-horizontal dotted line'in Figure 3: As the carriage is forced through the machine, and by virtue of the sloping face I4 of the carriage, it will 'baseenlespecially from Figure 3 that a certain pitch thereby cut on the propeller blade, since the member I5..is clamped upon the sloping sinface of the-carriage',y and the pitch will be exactly the same-as the slope I4. Also since thel carriage I3"is'high atthev forward end, the thickness of theeblade will-taper from the end gradually to a larger thickness at the hub. As the carriage is forcedl through the cutting blades, the trip lever 2201 course', travels together with= thesame. A pin 68 is secured inside ofthe vangle'memlcers; 41-slightly above the center; line ofthe machine. When the lever 22. strikes. thepinf,Y (see Figures .'73` and 8), itis carried over, as shownfiniFigure. 8, and since the square portions 2D and I8 are offcenter, they will-riseto the position asshown'in Figure 8, thereby causingthecarriage-I3fto drop;4 downwardly within thechannelf I'I: The. pin: 68:

is; so -situatedthat this droppingactionvoccurs asi soonas the bladesapproach-the hubportion-of the propellers'where, of courseit is-znoty desired' to cut. This dropping action thencccurs, which causes the strip I5,` toy clear the bladessothat the hub portion is` left intact. to itsV desiredfthickness.

After one blade of the propeller is'cut,l it is re,- moved and then.thelother` blade-isl clamped iny the same-position, andthe operation-.is repeated, therebyproviding` an oppositely pitchedslope on each-blade, whichpitch-willbe accurate fromthe tip to thehub. Afterl the pitch iscut,v the blade is then ready for the next operation which takes place -inthe airfoil cutter.

The airfoil cutterA is the upper machine as shown in Figure--2, and is identical in every re-y spect withfthe pitch' cutter, withzthe'exception of I theblades andfthe-slopefof-,the carriage: I3.v Af similar carriage I3 :isemployed vinthe airfoilgcut.- ter, with the exception ,that-the carriage I-3finthisr instance is rectangular throughout4 its cross-.secticnand dOesnot'incIude the slope I4, but.V instead the upper surface is. horizontal. The car-y riage I3, however, tapers downwardly from" the forward end to a more. pronounced-degree thanA in i.

the-pitch cutter, and-'which taper. is indicated i by the-dotted lines 69:. Attachedto asimilar .block 38. are theY blades; 10 (-.'see l1?ig.ureI 6.)., into.'

which :bla-:les `are formedtheairfoil `:curve -1 I having a suitable bevel 12. Thev` curve 1I includesthe smaller arcuate portion- 13AY andthe length. cned airfoil curve 14. 'I'llefcurve` portion; 1,3fis. at.,a1substantial depth. corresponding-1to1 orV greater than the full thicknessfof-thepropeller blade;-, Itlwillbe seen from Figure that asfthe carriage I3.- travels` past. the'f cutting blades in theffsame fashion as in the pitch cutter, that arstthe;

accuratelylffollow` the :thicker portion as well as the wid-er portion ofthe blades. As shown in Figure-6, .theibladei is in approximately its midposition ,of:,.cutting, and as thecarriage is :fed into-the machine, the-shape `of bladewill1be cut as shown bythe dotted lines 15,'so that an accurate-airfoihcurvewill be cut on the propeller, regardless of its increase in thickness and width. The same trip .lever `22, with its associated mechanisrngisiemployedLin the airfoil cutter so that the hub portion will again be released from the cutting blades in the same manner. lAfter the airfoil is cut on one blade or one-half of the propeller, it is removed, and the other end is clamped to the carriage, and it is forced through the machine in the same manner. l

The chip breaker plate in this instance is exactly similar to the other, with the exception that the edge 60, instead of being straight, is curved to approximately the same curve as the curve 1| in the plate 10, so that the edge will perform the same function in preventing the breaking off of large pieces and will always be close to the cutting edges.

It will be understood throughout the description that besides explaining the mechanical arrangements for performing the operations, that we have provided a process also for shaping propeller blades, which process utilizes the principle of accurately curved blades rotating at a high speed to cut the desired shapes.

It will now be seen that we have provided a machine for shaping wooden propellers, which shapes both the pitch and the airfoil curve of the propeller, which provides an accurate pitch and airfoil curve at all points regardless of thickness o-r width, and which machine is of simple construction which can be manufactured at a very reasonable cost.

Some changes may be made in the construction and arrangement of the parts of our invention without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims any modified forms of structure or use of mechanical equivalents, which may be reasonably included within their scope.

We claim as our invention:

l. An airfoil cutting machine comprising a channel, a carriage received within the channel, means for attaching a propeller blank to the carriage, and means for cutting an airfoil curve on said blank mounted on said channel including a rotating block including an opposed pair of blades attached thereto having cutting edges substantially of the same contour as the airfoil curve to be cut, said curve varying progressively along its depth and width so as to cut an accurate curve on said propeller regardless of the varying thickness and width of the same, said carriage sloping downwardly along its length on the upper surface thereof to cause accurate cutting with respect to the tapering thickness of said propeller, means for dropping said carriage below the level of said cutting blades when above the hub portion of the propeller including a pair of opposed guide members, a rotatable shaft attached at the inner end of said carriage, extensions eccentrically mounted on said shaft and received within the guide members, a trip member attached to said shaft and to one of said extensions, a pin attached inwardly of said channel adapted to force said trip member pivotally about said shaft to cause the shaft to drop during forward movement of the carriage.

2. A pitch cutting machine comprising a channel, a carriage received within the channel, means for attaching a blank wood strip to the carriage, and means for cutting a propeller pitch on said blank strip mounted on said channel including a horizontal cutting member mounted on said channel, said carriage being sloped downwardly across its width on the upper surface thereof, said slope being the same as the pitch to be cut, and said carriage being higher at its forward end to accommodate the tapering thickness of a propeller blade, means for dropping said carriage below the level of said cutting blades when above the hub portion of the propeller including a pair of opposed guide members, a rotatable shaft attached at the inner end of said carriage, extensions eccentrically mounted on said shaft and received within the guide members, a trip member attached to said shaft and to one of said extensions, a pin attached inwardly of said channel adapted to force said trip member pivotally about said shaft to cause the shaft to drop during forward movement of the carriage.

3. A pitch cutting machine comprising a channel, a carriage received within the channel, means for attaching a blank wood strip to the carriage, and means for cutting a propeller pitch on said blank strip including a horizontal cutting member mounted on said channel, said carriage being sloped downwardly across its width on the upper surface thereof, said slope being the same as the pitch to be cut, and said carriage being higher at its forward end to accommodate the tapering thickness of a propeller blade, means for dropping said carriage below the level of said cutting blades when above the hub portion of the propeller including a pair of opposed guide members, a rotatable shaft attached at the inner .end of said carriage, extensions eccentrically mounted on said shaft and received within the guide members, means for rotating said extensions about said center to cause dropping of the carriage during forward movement thereof.

4. A pitch cutting machine comprising a channel, a carriage received within the channel, means for attaching a blank wood strip to the carriage, and means for cutting a propeller pitch on said blank strip mounted on said channel including a horizontal cutting member mounted on said channel, said carriage being sloped downwardly across its width on the upper surface thereof, said slope being the same as the pitch to be cut, and said carriage being higher at its forward end toaccommodate the tapering thickness of a propeller blade, means for dropping said carriage below the level of said cutting blades when above the hub portion of the propeller including a pair of opposed guide members, a rotatable shaft attached at the inner end of said carriage, extensions eccentrically mounted on said shaft and received within the guide members, means for rotating said extensions about said center including a trip lever attached to the shaft, a pin attached to said channel for rotating said lever when forced thereagainst, to cause dropping of the carriage during forward movement thereof.

5. An airfoil cutter comprising a channel, a carriage received within the channel, means for attaching a propeller blank to the carriage, and means for cutting an airfoil curve on said blank mounted on said channel including a horizontal cutting member mounted on said channel having cutting edges substantially of the same contour as the airfoil curve to be cut, said curve varying progressively along its depth and width so as to cubain-accurate curveonzsaid propeller regardf less of the varyingv thickness and width of: the same, said. carriagev sloping downwardly) along its length on theupper surfacesthereof; to cause accurate cutting With.. respectv to; the. tapering rthickness ofY said. propeller, means for dropping saidscarriage'below the level of saidcuttingnblades when above the hub portiony of the propeller including a pair of opposed guide members, a roflU tatable shaft attached' at; the inner end-.of said 

